generators

JavaScript_Advance/generators.js

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+/*
+ Generators are functions with the possibility of exit and subsequent entry.
+ Their execution context (variable values) is preserved on subsequent inputs.
+*/
+
+// Let's consider a simple example:
+function* myGenerator() {
+ yield 5
+ yield 6
+}
+
+// In the example above, we wrote a simple generator function with asteriks(*) notation.
+// Next to the yield we put values that are going to be extracted from the function
+// In order to extract them one by one, we should at first call myGenerator function
+
+const gen = myGenerator()
+
+// The returning value of myGenerator function is a object-iterator. It has next() method
+// Which we may call to get the current generator function value:
+
+gen.next().value // 5
+
+// We get the value field of 'next' method's returning value, wich is an object as well
+// Let's call this again in order to get the next value:
+
+gen.next().value // 6
+
+// After we iterate through all the values, the next value is going to be undefined.
+
+gen.next().value // undefined.